Lubalt

how do i get my drawn image to the middle of the canvas without re-doing it?? pls help!

Also i drew it myself so its lines and i filled in things with the fill tool bucket thingy

I need some help because i was making a profile picture for YouTube and then i realised the pixels were too small so i enlarged it but my picture didnt and i dont know how to enlarge the image too (I made the image myself and its a square head) so please help me!!